Parallel MOSFET Class C RF Amplifier

RF power amplifiers in modern wireless communication devices is one key component in radar, electronic navigation equipment, communication and other areas of satellite communications has wide application. Power amplifier is important equipment in converting the DC power to AC power which has had a great development in the way of high frequency, low power loss, high power capability, and high efficiency. In this subject power MOSFET is used as the core component in the class C power amplifier in order to improve the efficiency and frequency and also to get high output power with high frequency.Power MOSFET by its merits of good high frequency characteristic, high switch speed, low switch loss, high input impedance and so on is widely used. However the limited capacity of the single power MOSFET has become a serious problem which waits to be solved. The issue through parallel MOSFET to expand the current capacity, this topic designs a kind of power amplifier which use power MOSFET in series as its core component and work in the state of class C. The main work of the topic course is divided into three parts, namely:conceive outline of the electric circuit structure and choice of use; the design of the driver circuit according to the structure; the study and the research on the electric circuit structure MOSFET parallel current-balancing.MOSFET's DC voltage-current characteristic, the capacitance between the poles, temperature characteristic and so on are extremely significant influence to the driving signal, therefore according to power MOSFET's requirements on the drive circuit, the circuit of the sine wave generation circuit, signal amplifier circuit is designed. Experimental results show the feasibility of the driver circuit.This subject designs a kind of RF power amplifier whose request single phase input, out power is 100W. It adopts two MOSFETs of ARF461 which is produced by MAX corporation connects in parallel, works under the class C, and operates at 10 MHz frequency. Through calculating, provide the design parameters of the system, and finally gives the results of the circuit simulation debug. Power MOSFET in parallel to increase current capacity of the system will appear the damage problem in the practical application because of parallel MOSFET current is not balanced. The text makes a detailed analysis of the factors in influencing MOSFET in parallel, and put forward a kind of comparatively simple and effective solution, then revises the parameter of the designed key circuit according to the solution to make the MOSFETs in parallel work better under the state of current balancing.